Apparatus and methods for monitoring a subject

ABSTRACT

Apparatus and methods are described for monitoring a subject. A sensor is configured to monitor the subject without contacting the subject or clothes the subject is wearing, and without viewing the subject or clothes the subject is wearing, and to generate a sensor signal in response to the monitoring. A computer processor is configured to: (a) receive the sensor signal, (b) extract from the sensor signal a plurality of heartbeats of the subject, and, for each of the extracted heartbeats, an indication of a quality of the extracted heartbeat, (c) select a subset of heartbeats, based upon the qualities of the extracted heartbeats, (d) for only the subset of heartbeats, determine interbeat intervals between adjacent heartbeats, (e) in response thereto, determine a physiological state of the subject, and (f) generate an output in response thereto. Other applications are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication 62/295,077, entitled “Apparatus and method for monitoring asubject,” filed Feb. 14, 2016.

The present application is related to an International PatentApplication, entitled “Apparatus and methods for monitoring a subject,”being filed on even date herewith. Each of the above referencedapplications is incorporated herein by reference.

FIELD OF EMBODIMENTS OF THE INVENTION

The present invention relates generally to monitoring a subject.Specifically, some applications of the present invention relate tomonitoring a subject, while the subject is in a vehicle.

BACKGROUND

Quality and duration of sleep plays an important role in overallphysical and psychological wellbeing. Unfortunately, many subjects havedifficulty falling or staying asleep. Thermoregulation during sleepaffects sleep quality.

An article entitled “Mechanisms and functions of coupling between sleepand temperature rhythms,” by Van Someren (Prog Brain Res 2006,153:309-324) describes heat production and heat loss as showingcircadian modulation. The article states that sleep preferably occursduring the circadian phase of decreased heat production and increasedheat loss, the latter due to a profound increase in skin blood flow and,consequently, skin warming.

An article entitled “Functional link between distal vasodilation andsleep-onset latency,” by Krauchi et al. (Am J Physiol Regul Integr CompPhysiol 2000, 278:R741-R748) describes a study in which the role of heatloss in sleep initiation was evaluated. The article states that thestudy provides evidence that selective vasodilation of distal skinregions (and hence heat loss) promotes the rapid onset of sleep.

An article entitled “Skin temperature and sleep-onset latency: Changeswith age and insomnia,” by Raymann et al. (Physiology & Behavior 90(2007) 257-266) states that changes in skin temperature may causallyaffect the ability to initiate and maintain sleep. The article describesfindings on the relation between skin temperature and sleep-onsetlatency, indicating that sleep propensity can be enhanced by warming theskin to the level that normally occurs prior to, and during, sleep. Thearticle describes a study to investigate whether different methods offoot warming could provide an applicable strategy to address sleepcomplaints.

SUMMARY OF EMBODIMENTS

For some applications, a sensor unit is disposed under a seat of avehicle. The sensor unit is configured to monitor physiologicalparameters of a subject who is sitting on the seat, and to generate asensor signal in response thereto. Typically, the subject is an operatorof the vehicle (e.g., the driver of a car, the pilot of an airplane, thedriver of a train, etc.). A computer processor is configured to receiveand analyze the sensor signal for any one of a number of reasons.Typically, the computer processor derives vital signs of the subject(such as heart rate, respiratory rate, and/or heart-rate variability)from the sensor signal. For some applications, the computer processorcompares the subject's vital signs to a baseline of the subject that wasderived during occasions when the subject previously operated thevehicle. In response thereto, the computer processor may determine thatthe subject's vital signs have changed substantially from the baseline,that the subject is unwell, drowsy, asleep, and/or under the influenceof drugs or alcohol. In response thereto, the computer processor maygenerate an alert to the driver, or to a remote location (such as to afamily member, and/or to a corporate control center). Alternatively oradditionally, the computer processor may automatically disable thevehicle.

For some applications, the sensor unit is configured to be placedunderneath the seat and to detect motion of the subject who is sittingon the seat during motion of the vehicle. The sensor unit typicallyincludes a housing, at least one first motion sensor disposed within thehousing, such that the first motion sensor generates a first sensorsignal that is indicative of the motion of the vehicle, and at least onesecond motion sensor disposed within the housing, such that the secondmotion sensor generates a second sensor signal that is indicative of themotion of the subject and the motion of the vehicle. The computerprocessor is typically configured to at least partially distinguishbetween the motion of the subject and the motion of the vehicle byanalyzing the first and second sensor signals.

For some applications of the present invention, a temperature controldevice (such as an electric blanket, or an electric mattress) includesat least first and second sections corresponding to respective portionsof a body of a single subject. For example, a blanket may include threetypes of sections: a trunk section corresponding to the subject's trunk,leg sections corresponding to the subject's legs, and arm sectionscorresponding to the subject's arms. A temperature-regulation unitregulates respective portions of the subject's body to be at respectivetemperatures by, simultaneously, setting a temperature of the firstsection of the temperature control device to a first temperature, andsetting a temperature of the second section of the temperature controldevice to a second temperature that is different from the firsttemperature. Optionally, the temperature-regulation unit sets thetemperature of additional sections of the temperature control device tofurther respective temperatures.

As described hereinabove, thermoregulation during sleep affects sleepquality. Moreover, as described in the Krauchi article for example,selective vasodilation of distal skin regions (and hence heat loss) maypromote the onset of sleep. For some applications, a computer processordrives the temperature-regulation unit to regulate respective portionsof the subject's body to be at respective temperatures in the mannerdescribed herein, such as to improve sleep quality, shorten sleeplatency, and/or better maintain sleep continuity. For example, thecomputer processor may drive the temperature-regulation unit to regulatethe temperature of the subject's legs and/or arms to be at a greatertemperature than the subject's trunk (e.g., by heating the legs and/orarms by more than the trunk, or by cooling the trunk by less than thelegs and/or arms). For some applications, the computer processor drivesthe temperature-regulation unit to regulate respective portions of thesubject's body to be at respective temperatures, in response to thesubject's sleep stage, which is detected automatically by analyzing asensor signal from a sensor (such as motion sensor) that is configuredto monitor the subject.

There is therefore provided, in accordance with some applications of thepresent invention, apparatus for use with a seat of a vehiclecomprising:

a sensor unit configured to be placed underneath the seat and configuredto detect motion of a subject who is sitting on the seat during motionof the vehicle, the sensor unit comprising:

-   -   a housing;    -   at least one first motion sensor disposed within the housing,        such that the first motion sensor generates a first sensor        signal that is indicative of the motion of the vehicle;    -   at least one second motion sensor disposed within the housing,        such that the second motion sensor generates a second sensor        signal that is indicative of the motion of the subject and the        motion of the vehicle; and

a computer processor configured to at least partially distinguishbetween the motion of the subject and the motion of the vehicle byanalyzing the first and second sensor signals.

For some applications, the first motion sensor is disposed within thehousing such that the first motion sensor is isolated from the motion ofthe subject, such that the first motion sensor only detects motion thatis due to motion of the vehicle.

For some applications, the computer processor is configured to:

derive the motion of the vehicle from the first sensor signal, and

based upon the derived motion of the vehicle, to subtract, from thesecond sensor signal, a portion of the second sensor signal that isgenerated by the motion of the vehicle.

For some applications:

at least a portion of the housing is flexible,

the apparatus further comprises a fluid compartment disposed on an innersurface of the housing,

the at least one first motion sensor is disposed on a surface of thefluid compartment, and

at least one second motion sensor is disposed on at least one innersurface of the flexible portion of the housing.

For some applications, the first motion sensor comprises a sensorselected from the group consisting of: a deformation sensor, apiezoelectric sensor, and an accelerometer.

For some applications, the second motion sensor comprises a sensorselected from the group consisting of: a deformation sensor, apiezoelectric sensor, and an accelerometer.

For some applications, the at least one second motion sensor comprisestwo or more second motion sensors disposed on respective inner surfacesof the flexible portion of the housing.

For some applications:

the housing comprising flexible and rigid portions;

the at least one first motion sensor is disposed on at least one innersurface of the rigid portion of the housing;

the at least one second motion sensor is disposed on at least one innersurface of the flexible portion of the housing, and configured togenerate a second sensor signal.

For some applications, the first motion sensor comprises a sensorselected from the group consisting of: a deformation sensor, apiezoelectric sensor, and an accelerometer.

For some applications, the second motion sensor comprises a sensorselected from the group consisting of: a deformation sensor, apiezoelectric sensor, and an accelerometer.

For some applications, the at least one first motion sensor comprisestwo or more first motion sensors disposed on respective inner surfacesof the rigid portion of the housing.

For some applications, the at least one second motion sensor comprisestwo or more second motion sensors disposed on respective inner surfacesof the flexible portion of the housing.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with a seat of a vehicle including:

a sensor unit configured to be placed underneath the seat and configuredto detect motion of a subject who is sitting on the seat during motionof the vehicle, the sensor unit comprising:

-   -   a housing at least a portion of which is flexible;    -   a fluid compartment disposed on an inner surface of the housing;    -   at least one first motion sensor disposed on a surface of the        fluid compartment, and configured to generate a first sensor        signal;    -   at least one second motion sensor disposed on at least one inner        surface of the flexible portion of the housing, the second        motion sensor being configured to generate

a second sensor signal; and

a computer processor configured to at least partially distinguishbetween the motion of the subject and the motion of the vehicle byanalyzing the first and second sensor signals.

In some applications, the first motion sensor includes a sensor selectedfrom the group consisting of: a deformation sensor, a piezoelectricsensor, and an accelerometer.

In some applications, the second motion sensor includes a sensorselected from the group consisting of: a deformation sensor, apiezoelectric sensor, and an accelerometer.

In some applications, the at least one second motion sensor includes twoor more second motion sensors disposed on respective inner surfaces ofthe flexible portion of the housing.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with a seat of a vehicle including:

a sensor unit configured to be placed underneath the seat and configuredto detect motion of a subject who is sitting on the seat during motionof the vehicle, the sensor unit comprising:

-   -   a housing comprising flexible and rigid portions;    -   at least one first motion sensor disposed on at least one inner        surface of the rigid portion of the housing, and configured to        generate a first sensor signal;    -   at least one second motion sensor disposed on at least one inner        surface of the flexible portion of the housing, and configured        to generate a second sensor signal; and

a computer processor configured to at least partially distinguishbetween the motion of the subject and the motion of the vehicle byanalyzing the first and second sensor signals.

In some applications, the first motion sensor includes a sensor selectedfrom the group consisting of: a deformation sensor, a piezoelectricsensor, and an accelerometer.

In some applications, the second motion sensor includes a sensorselected from the group consisting of: a deformation sensor, apiezoelectric sensor, and an accelerometer.

In some applications, the at least one first motion sensor includes twoor more first motion sensors disposed on respective inner surfaces ofthe rigid portion of the housing.

In some applications, the at least one second motion sensor includes twoor more second motion sensors disposed on respective inner surfaces ofthe flexible portion of the housing.

There is additionally provided, in accordance with some applications ofthe present invention, apparatus including:

a temperature-control device comprising at least first and secondsections corresponding to respective portions of a body of a singlesubject; and

a temperature-regulation unit configured to regulate temperatures of therespective portions of the subject's body to be at respectivetemperatures by, simultaneously, setting a temperature of the firstsection of the temperature-control device to a first temperature, andsetting a temperature of the second section of the temperature controldevice to a second temperature that is different from the firsttemperature.

In some applications, the temperature control device includes a deviceselected from the group consisting of: a blanket and a mattress, and theselected device has a length of less than 250 cm, and a width of lessthan 130 cm.

In some applications, the temperature control device includes a blanketconfigured to be placed above the subject, and the first and secondsection include first and second sections that are configured to beplaced over respective portions of the subject's body.

In some applications, the temperature control device includes a blanketconfigured to be disposed underneath the subject, and the first andsecond section include first and second sections that are configured tobe disposed underneath respective portions of the subject's body.

In some applications, the temperature control device includes a mattressconfigured to be disposed underneath the subject, and the first andsecond section include first and second sections that are configured tobe disposed underneath respective portions of the subject's body.

In some applications, the first section corresponds to a trunk of thesubject, and the second section corresponds to a distal portion of thesubject's body selected from the group consisting of: at least one armof the subject, and at least one leg of the subject.

In some applications, the apparatus further includes:

a sensor, configured to monitor the subject and generate a sensor signalin response thereto; and

a computer processor, configured to:

-   -   analyze the signal,    -   in response thereto, identify a sleep stage of the subject, and    -   in response to the identified sleep stage, drive the        temperature-regulation unit to regulate the temperatures of the        respective portions of the subject's body to be at the        respective temperatures.

In some applications, the computer processor is configured to:

differentially identify at least two sleep stages selected from thegroup consisting of: a falling-asleep stage, a beginning-sleep stage, amid-sleep stage, a premature-awakening stage, an awakening stage, alight sleep stage, a slow-wave sleep stage, and a rapid-eye-movementsleep stage, and

in response to the differentially identified sleep stages, drive thetemperature-regulation unit to regulate the temperatures of therespective portions of the subject's body to be at the respectivetemperatures.

In some applications, the sensor is configured to monitor the subjectwithout contacting or viewing the subject, and without contacting orviewing clothes the subject is wearing.

In some applications, the first section corresponds to a trunk of thesubject, and the second section corresponds to at least one distalportion of the subject's body selected from the group consisting of: atleast one arm of the subject, and at least one leg of the subject.

In some applications, the computer processor is configured, in responseto detecting that the subject is trying to fall asleep, to drive thetemperature-modulation unit to regulate the subject's trunk to be at afirst temperature, and to regulate at least the selected distal portionof the subject's body to be at a second temperature that is greater thanthe first temperature.

In some applications, the computer processor is configured, in responseto detecting that the subject is at a sleep stage at which it issuitable to wake up the subject, to drive the temperature-regulationunit to heat the subject's trunk.

In some applications, the sensor includes a motion sensor configured tosense motion of the subject.

In some applications, the sensor is configured to monitor the subjectwithout contacting or viewing the subject, and without contacting orviewing clothes the subject is wearing.

In some applications, the apparatus is for use with a room-climateregulation device, and, in response to the identified sleep stage, thecomputer processor is further configured to adjust a parameter of theroom-climate regulation device.

In some applications, the room-climate regulation device includes anair-conditioning unit, and, in response to the identified sleep stage,the computer processor is configured to adjust a parameter of theair-conditioning unit.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with an output device, theapparatus including:

a sensor, configured to monitor a subject, during a sleeping session ofthe subject, and to generate a sensor signal in response to themonitoring; and

a computer processor, configured to:

-   -   analyze the signal,    -   in response thereto, identify a correspondence between positions        of the subject and occurrences of apnea events of the subject        during the sleeping session, and    -   generate an output on the output device, in response to the        identified correspondence.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with a female subject, theapparatus including:

a sensor, configured to monitor the subject, prior to the subjectbecoming pregnant and during a pregnancy of the subject, and to generatea sensor signal in response to the monitoring; and

a computer processor, configured to:

-   -   analyze the sensor signal,    -   based upon the sensor signal generated by the sensor in response        to the monitoring prior to the subject becoming pregnant, to        determine a baseline heart rate for the subject,    -   based upon the baseline heart rate, define a pregnancy heart        rate measure, which is indicative of one or more heart rates        that the subject is expected to have during a healthy pregnancy,    -   based upon the sensor signal generated by the sensor in response        to the monitoring during the subject's pregnancy, determine a        heart rate of the subject during the pregnancy,    -   compare the subject's heart rate during the pregnancy to the        pregnancy heart rate measure, and    -   generate an output on the output device, in response to the        comparison.

There is further provided, in accordance with some applications of thepresent invention, apparatus for use with a stimulus-providing devicethat is configured to provide a stimulus to a subject selected from thegroup consisting of: an audio stimulus, a visual stimulus, and a tactilestimulus, the apparatus including:

a sensor configured to monitor a subject and to generate a sensor signalin response thereto; and

a control unit configured to:

-   -   analyze the sensor signal,    -   modulate a property of the stimulus that is provided to the        subject by the stimulus-providing device, in response to (a) the        analyzing of the sensor signal, and (b) a historical        physiological parameter of the subject that was exhibited in        response to a historical modulation of the property of the        stimulus, and    -   drive the stimulus-providing device to provide the stimulus to        the subject.

There is additionally provided, in accordance with some applications ofthe present invention, apparatus for monitoring a subject, the apparatuscomprising:

a sensor, configured to monitor the subject without contacting thesubject or clothes the subject is wearing, and without viewing thesubject or clothes the subject is wearing, and to generate a sensorsignal in response to the monitoring; and

a computer processor, configured to:

-   -   receive the sensor signal,    -   extract from the sensor signal a plurality of heartbeats of the        subject, and, for each of the extracted heartbeats, an        indication of a quality of the extracted heartbeat,    -   select a subset of heartbeats, by selecting for inclusion in the        subset only heartbeats for which qualities of both the heartbeat        itself, and an adjacent heartbeat to the heartbeat, exceed a        threshold,    -   for only the subset of heartbeats, determining interbeat        intervals between adjacent heartbeats,    -   in response thereto, determining a physiological state of the        subject, and    -   generating an output in response thereto.

There is additionally provided, in accordance with some applications ofthe present invention, apparatus for monitoring a subject, the apparatuscomprising:

a sensor, configured to monitor the subject and to generate a sensorsignal in response thereto;

a plurality of filters configured to filter the sensor signal usingrespective filter parameters; and

a computer processor, configured to:

-   -   receive the sensor signal,    -   filter the signal with each of two or more of the filters,    -   in response to a quality of each of the filtered signal, select        one of the plurality of filters to filter the sensor signal,    -   subsequently:        -   detecting that the subject has undergone motion, by            analyzing the sensor signal,        -   in response thereto, filtering the signal with each of two            or more of the filters, and        -   in response to a quality of each of the filtered signal,            select one of the plurality of filters to filter the sensor            signal.

The present invention will be more fully understood from the followingdetailed description of applications thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of apparatus for monitoring asubject, in accordance with some applications of the present invention;

FIG. 2 is a schematic illustration of a blanket, in accordance with someapplications of the present invention;

FIG. 3 is a flowchart showing steps that are performed by a computerprocessor in order to control a subject's body temperature, inaccordance with some applications of the present invention;

FIG. 4 is a flowchart showing steps that are performed by a computerprocessor in order to monitor sleep apnea of a subject, in accordancewith some applications of the present invention;

FIG. 5 is a schematic illustration of a sensor unit disposed under theseat of a vehicle, in accordance with some applications of the presentinvention;

FIGS. 6A-C are schematic illustrations of a sensor unit as shown in FIG.5, in accordance with respective applications of the present invention;

FIGS. 7A-B are schematic illustrations of subject-monitoring apparatus,in accordance with some applications of the present invention;

FIG. 8 is a flowchart showing steps that are performed by a computerprocessor in order to monitor a subject who is pregnant, in accordancewith some applications of the present invention;

FIGS. 9A-C show histograms of patients' cardiac interbeat intervals thatwere recorded in accordance with some applications of the presentinvention; and

FIG. 10 shows components of a subject's cardiac cycle that were detectedin accordance with some applications of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is made to FIG. 1, which is a schematic illustration ofsubject-monitoring apparatus 20, in accordance with some applications ofthe present invention. Apparatus 20 is generally used to monitor asubject 24, while he or she is in his or her bed in a home setting. Forsome applications, the subject-monitoring apparatus is used in ahospital setting.

Subject-monitoring apparatus 20 comprises a sensor 22 (e.g., a motionsensor) that is configured to monitor subject 24. Sensor 22 may be amotion sensor that is similar to sensors described in U.S. Pat. No.8,882,684 to Halperin, which is incorporated herein by reference. Theterm “motion sensor” refers to a sensor that senses the subject's motion(e.g., motion due to the subject's cardiac cycle, respiratory cycle, orlarge-body motion of the subject), while the term “sensor” refers moregenerally to any type of sensor, e.g., a sensor that includes anelectromyographic sensor and/or an imaging sensor.

Typically, sensor 22 includes a sensor that performs monitoring of thesubject without contacting the subject or clothes the subject iswearing, and/or without viewing the subject or clothes the subject iswearing. For example, the sensor may perform the monitoring withouthaving a direct line of sight of the subject's body, or the clothes thatthe subject is wearing, and/or without any visual observation of thesubject's body, or the clothes that the subject is wearing. Furthertypically, the sensor performs monitoring of the subject withoutrequiring subject compliance (i.e., without the subject needing toperform an action to facilitate the monitoring that would not haveotherwise been performed). It is noted that, prior to the monitoring,certain actions (such as purchasing the sensor, placing the sensor underthe subject's mattress, downloading software for use with thesubject-monitoring apparatus, and/or configuring software for use withthe subject-monitoring apparatus) may need to be performed. The term“without requiring subject compliance” should not be interpreted asexcluding such actions. Rather the term “without requiring subjectcompliance” should be interpreted as meaning that, once the sensor hasbeen purchased, placed in a suitable position and activated, the sensorcan be used to monitor the subject (e.g., to monitor the subject duringrepeated monitoring sessions), without the subject needing to performany actions to facilitate the monitoring that would not have otherwisebeen performed.

For some applications, sensor 22 is disposed on or within the subject'sbed, and configured to monitor the subject automatically, while thesubject is in their bed. For example, sensor 22 may be disposedunderneath the subject's mattress 26, such that the subject is monitoredwhile she is lying upon the mattress, and while carrying out her normalsleeping routine, without the subject needing to perform an action tofacilitate the monitoring that would not have otherwise been performed.

A computer processor 28, which acts as a control unit that performs thealgorithms described herein, analyzes the signal from sensor 22.Typically, computer processor 28 communicates with a memory 29. For someapplications, computer processor 28 is embodied in a desktop computer30, a laptop computer 32, a tablet device 34, a smartphone 36, and/or asimilar device that is programmed to perform the techniques describedherein (e.g., by downloading a dedicated application or program to thedevice), such that the computer processor acts as a special-purposecomputer processor. For some applications, as shown in FIG. 1, computerprocessor 28 is a dedicated computer processor that receives (andoptionally analyzes) data from sensor 22, and communicates with computerprocessors of one or more of the aforementioned devices, which act asexternal devices.

For some applications, the subject (or another person, such as acare-giver) communicates with (e.g., sends data to and/or receives datafrom) computer processor 28 via a user interface device 35. Asdescribed, for some applications, computer processor is embodied in adesktop computer 30, a laptop computer 32, a tablet device 34, asmartphone 36, and/or a similar device that is programmed to perform thetechniques described herein. For such applications, components of thedevice (e.g., the touchscreen, the mouse, the keyboard, the speakers,the screen) typically act as user interface device 35. Alternatively, asshown in FIG. 1, computer processor 28 is a dedicated computer processorthat receives (and optionally analyzes) data from sensor 22. For somesuch applications, the dedicated computer processor communicates withcomputer processors of one or more of the aforementioned externaldevices (e.g., via a network), and the user interfaces of the externaldevices (e.g., the touchscreen, the mouse, the keyboard, the speakers,the screen) are used by the subject, as user interface device 35, tocommunicate with the dedicated computer processor and vice versa. Forsome applications, in order to communicate with computer processor 28,the external devices are programmed to communicate with the dedicatedcomputer processor (e.g., by downloading a dedicated application orprogram to the external device).

For some applications, user interface includes an input device such as akeyboard 38, a mouse 40, a joystick (not shown), a touchscreen device(such as smartphone 36 or tablet device 34), a touchpad (not shown), atrackball (not shown), a voice-command interface (not shown), and/orother types of user interfaces that are known in the art. For someapplications, the user interface includes an output device such as adisplay (e.g., a monitor 42, a head-up display (not shown) and/or ahead-mounted display (not shown)), and/or a different type of visual,text, graphics, tactile, audio, and/or video output device, e.g.,speakers, headphones, smartphone 36, or tablet device 34. For someapplications, the user interface acts as both an input device and anoutput device. For some applications, the processor generates an outputon a computer-readable medium (e.g., a non-transitory computer-readablemedium), such as a disk, or a portable USB drive.

Reference is now made to FIG. 2, which is a schematic illustration of atemperature control device, e.g., a blanket 50 (which is typically anelectric blanket), in accordance with some applications of the presentinvention. The temperature control device includes at least first andsecond sections corresponding to respective portions of a body of asingle subject. For example, as shown the blanket includes three typesof sections: a trunk section 52 corresponding to the subject's trunk,leg sections 54 corresponding to the subject's legs, and arm sections 56corresponding to the subject's arms. A temperature-regulation unit 58regulates respective portions of the subject's body to be at respectivetemperatures by, simultaneously, setting the temperature of the firstsection of the temperature control device to a first temperature, andsetting the temperature of the second section of the temperature controldevice to a second temperature that is different from the firsttemperature, and, optionally, setting the temperatures of additionalsections of the temperature control device to further respectivetemperatures.

It is noted that blanket 50 can be an over-blanket that is placed overthe subject's body, or an under-blanket that is placed above thesubject's mattress and beneath the subject (as shown). Furthermore, thescope of the present invention includes any temperature control devicethat includes first and second sections corresponding to respectiveportions of a body of a single subject, for use with atemperature-regulation unit that regulates the respective portions ofthe subject's body to be at respective temperatures by, simultaneously,setting the temperature of the first section of the temperature controldevice to a first temperature, and setting the temperature of the secondsection of the temperature control device to a second temperature thatis different from the first temperature. For example, the temperaturecontrol device may include a mattress (e.g., an electric mattress),which includes built-in heating pads.

As described hereinabove, thermoregulation during sleep affects sleepquality. Moreover, as described in the Krauchi article, for example,selective vasodilation of distal skin regions (and hence heat loss) maypromote the onset of sleep. For some applications, the computerprocessor drives the temperature-regulation unit to regulate thetemperatures of respective portions of the subject's body to be atrespective temperatures, in the manner described herein, such as toimprove sleep quality, shorten sleep latency, and/or better maintainsleep continuity. For example, the computer processor may drive thetemperature-regulation unit to heat the subject's legs and/or arms to agreater temperature than the subject's trunk. For some applications, thecomputer processor may drive the temperature-regulation unit to cool oneor more portions of the subject's body. For some applications, thecomputer processor drives the temperature-regulation unit to heat and/orcool respective portions of the subject's body to respectivetemperatures, in response to the subject's sleep stage, which isdetected automatically by analyzing the sensor signal from sensor 22.

Reference is now made to FIG. 3, which is a flowchart showing steps thatare performed by a computer processor in order to control a subject'sbody temperature, in accordance with some applications of the presentinvention. In a first step 60, the computer processor receives a signalfrom sensor 22, which is typically as described hereinabove. In a secondstep 62, the computer processor analyzes the sensor signal in order todetermine the subject's current sleep stage. For example, the computerprocessor may determine that the subject is currently in afalling-asleep stage (prior to falling asleep), a beginning-sleep stage,a mid-sleep stage, an awakening stage, a premature awakening stage, anREM stage, or a slow-wave stage. For some applications, the sleep stageis detected based upon the sensor signal using techniques as describedin US 2007/0118054 to Pinhas (now abandoned), which is incorporatedherein by reference. In response to the analysis of the sensor signal,the computer processor (in step 64) adjusts the temperature of a firstportion of the temperature-control device (e.g., the arm or leg portionof blanket 50), and/or separately (in step 66) adjusts the temperatureof a second portion of the temperature-control device (e.g., the trunkportion of blanket 50). For some applications (in step 68), the computerprocessor additionally adjusts the temperature of an additionalroom-climate regulation device, such as an air-conditioning unit (e.g.,unit 44, FIG. 1), an electric heater, and/or a radiator. For example,the air-conditioning unit may be used to provide additional control ofthe temperature of the subject's trunk by controlling the temperature ofthe air that the subject inhales.

For some applications, in response to the computer processor determiningthat the subject is at the start of a sleeping session (e.g., in afalling-asleep stage or a beginning-sleep stage), the computer processordrives the temperature-regulation unit to heat distal parts of thesubject's body (e.g., the subject's arms and/or legs) to a highertemperature than the subject's trunk. Typically, the computer processorwill use different temperature profiles for different sleep states. Forexample, when the subject is in slow wave sleep, the computer processormay drive the temperature-regulation unit to keep temperatures lowerthan during other phases of the subject's sleep. Alternatively oradditionally, when the subject wakes up during the night the computerprocessor may use a similar profile to that used when the subject isinitially trying to fall asleep.

For some applications, the computer processor drives thetemperature-regulation unit to warm the subject's trunk in order togently wake up the subject. For example, the computer processor may usetrunk warming to wake up the subject, based on having received an inputof a desired time for the subject to wake up (e.g., via the userinterface), or based on detecting that the current sleep phase of thesubject is such that it would be a good time to wake up the subject.

For some applications, a user designates temperature profilescorresponding to respective sleep stages, via a user input into thecomputer processor. Typically, the temperature profile of any sleepstage will include respective temperatures for respective portions ofthe subject's body, and/or differences between the temperatures to whichrespective portions are heated or cooled. Alternatively or additionally,the computer processor utilizes a machine learning algorithm, based uponwhich the computer processor analyzes the subject's response todifferent temperature profiles at different sleep stages and learnswhich temperature profiles at which sleep phases result in the bestquality sleep for the subject. Typically, for such applications, basedupon the aforementioned analysis, the computer processor automaticallydesignates temperature profiles to respective sleep stages.

As described hereinabove, for some applications, the computer processoradditionally adjusts the temperature of an additional room-climateregulation device, such as an air-conditioning unit, an electric heater,and/or a radiator. For example, an air-conditioning unit may be used toprovide additional control of the temperature of the subject's trunk bycontrolling the temperature of the air that the subject inhales. Forsome applications, the temperature profiles of the respective sleepstages include a setting for the additional room-climate regulationdevice.

Referring again to FIG. 2, it is noted that typically blanket is sizedfor use with a single subject, and includes separate regions thetemperatures of which are controlled separately from one another.Typically, the length of the blanket is less than 250 cm, e.g., lessthan 220 cm, or less than 200 cm, and the width of the blanket is lessthan 130 cm, e.g., less than 120 cm, or less than 110 cm. Forapplications, in which the temperature-control device for use with asingle subject is a mattress, typically, the mattress has similardimensions to those described with respect to the blanket.

For some applications, the temperature control device is a portion of ablanket or a mattress that is suitable for being used by two subjects(e.g., partners in a double bed). Even for such applications, a portionof the blanket or mattress that is configured to be placed underneath orover a single subject (e.g., a left half of the blanket, or a left halfof the mattress) includes at least first and second sections (e.g., atrunk section corresponding to the subject's trunk, leg sectionscorresponding to the subject's legs, and/or arm sections correspondingto the subject's arms), and the temperature-regulation unit regulatesthe respective portions of the subject's body to be at respectivetemperatures by, simultaneously, setting the temperature of the firstsection of the temperature control device to a first temperature, andsetting the temperature the second section of the temperature controldevice to a second temperature that is different from the firsttemperature, and, optionally, setting the temperature of additionalsections of the temperature control device to further respectivetemperatures.

Typically, the techniques described herein are practiced in combinationwith techniques described in WO 16/035073 to Shinar, which isincorporated herein by reference. For example, the computer processormay drive the user interface to prompt the subject to input changes tothe temperature profiles corresponding to respective sleep stages, inresponse to a change in a relevant parameter. For example, in responseto a change in season, an ambient temperature, an ambient humidity,and/or a going-to-sleep time (e.g., the subject is going to bed at anunusual time), the computer processor may drive the user interface toprompt the subject to re-enter his/her temperature profiles. (Thecomputer processor may identify the change of the relevant parameter ina variety of ways, such as, for example, by receiving input from asensor, or by checking the internet.)

For some applications, in response to analyzing the sensor signal, thecomputer processor calculates a sleep score of the subject. For example,the computer processor may calculate a score from one or more parameterssuch as a time to fall asleep, duration of sleep, or “sleep efficiency,”which is the percentage of in-bed time during which the subject issleeping. For some applications, the score is calculated using one ormore of the aforementioned parameters, such that a higher sleep score isindicative of more restful sleeping session relative to a lower sleepscore. The computer processor may then compare the sleep score to abaseline value, e.g., an average sleep score over a previous period oftime. In response to the calculated sleep score being lower than thebaseline value, the computer processor may drive the user interface toprompt the subject to re-enter new temperature profiles for respectivesleep stages, since it is possible that the temperature profiles were acontributing factor in the subject's low sleep score. Alternatively oradditionally, the computer processor may drive user interface to promptthe subject to input at least one factor that may have caused the lowsleep score. The computer processor then controls the heating device inresponse to the input.

In some applications, the computer processor computes a measure ofrelaxation, i.e., a relaxation score, for the subject, one or more timesduring a sleeping session. For example, a high relaxation score may becomputed if the subject shows little movement, and little variation inboth respiration rate and respiration amplitude. The relaxation scoremay be used to compute the sleep score. Alternatively or additionally,in response to a low relaxation score, the computer processor mayimmediately adjust the temperature of sections of the temperaturecontrol device.

In some applications, in response to a low sleep score, the computerprocessor adjusts the temperature profiles even without any input fromthe user, or the computer processor generates an output (e.g., via userinterface device 35) that includes suggested temperature profiles, whichthe subject may edit and/or confirm via the user interface.

For some applications, when the temperature control device is initiallyused by the subject, the computer processor is configured to perform a“sweep” (or “optimization routine”) over a plurality of differenttemperature profiles at respective sleep stages, in order to ascertainwhich profiles at which sleep stages are conducive to a higher sleepscore, relative to other settings, e.g., which setting maximizes thesleep score. For example, over the course of several sleeping sessions,the computer processor may change the temperature profiles that are usedat respective sleep stages in different ways, and in response thereto,determine the optimal temperature profiles.

Additional techniques as described in WO 16/035073 to Shinar, which isincorporated herein by reference, may be practiced in combination withthe apparatus and methods described herein.

Reference is now made to FIG. 4, which is a flowchart showing steps thatare performed by computer processor 28 in order to monitor sleep apneaof the subject, in accordance with some applications of the presentinvention.

For some applications, sensor 22 is configured to monitor the subjectduring a sleeping session of the subject. The computer processorreceives and analyzes the sensor signal (step 70). Based on the analysisof the signal, the computer processor identifies the positions of thesubject's body at respective times during the sleeping session (step72). For example, the system may identify when during the sleepingsession the subject was lying on his/her side, when during the sleepingsession the subject was lying on his/her back (i.e., supine), and whenduring the sleeping session the subject was lying on his/her stomach.For some applications, the computer processor determines the positionsof the subject's body by analyzing the sensor signal using analysistechniques as described in U.S. Pat. No. 8,821,418 to Meger, which isincorporated herein by reference. For some applications, when thecomputer processor is first used for monitoring sleep apnea events, inaccordance with the procedure shown in FIG. 4, a calibration process isperformed by the processor. For example, the processor may instruct thesubject to lie on his/her back, side, and stomach, each for a given timeperiod. The processor analyzes the subject's cardiac and respiratoryrelated waveforms, and/or other signal components of the sensor signalthat are recorded when the subject is lying is respective positions.Based upon this analysis, the processor correlates respective signalcharacteristics to respective positions of the subject. Thereafter, theprocessor identifies the subject's position based upon characteristicsof the sensor signal.

In addition, based upon the analysis of the sensor signal, the computerprocessor identifies apnea events that occur during the sleeping session(step 74). For example, the computer processor may identify apnea eventsby analyzing the sensor signal using analysis techniques as described inUS 2007/0118054 to Pinhas (now abandoned), which is incorporated hereinby reference. In step 76, the computer processor identifies acorrespondence between positions of the subject and occurrences of apneaevents of the subject during the sleeping session. The computerprocessor typically generates an output on an output device (e.g., anyone of the output devices described with reference to FIG. 1), inresponse to the identified correspondence.

For example, the computer processor may generate an indication of:

(a) which positions cause the subject to undergo apnea events (e.g.,“Sleeping on your back causes apnea events to occur”),

(b) a recommended position for the subject to assume while sleeping(e.g. “Try sleeping on your side”), and/or

(c) recommended steps to take in order to reduce the likelihood of apneaevents occurring (e.g., “Try sleeping with a ball strapped to yourback”).

For some applications, the analysis of the sensor signal (step 70), theidentification of subject positions (step 72), the identification ofapnea events (step 74), and/or the identification of correspondencebetween the apnea events and the subject positions (step 76) areperformed in real time, as the sensor signal is received by theprocessor. Alternatively, one or more of the aforementioned steps areperformed subsequent to the sleeping session.

For some applications, in response to detecting that the subject islying in a given position that the processor has determined to cause thesubject to undergo apnea events, the computer processor generates analert and/or nudges the subject to change positions. For example, inresponse to detecting that the subject is in a supine position (andhaving determined that lying in this position causes the subject toundergo apnea events), the computer processor may cause the subject'sbed to vibrate, or may adjust the tilt angle of the bed or a portionthereof.

For some applications, techniques described herein are practiced incombination with techniques described in US 2007/0118054 to Pinhas,which is incorporated into the present application by reference. Forexample, the apparatus described herein may be used with a bed ormattress with an adjustable tilt angle, and/or an inflatable pillowwhich, when activated, inflates or deflates to vary the elevation of thehead of the subject as desired. For some applications, in response todetecting that the subject is lying in a given position that theprocessor has determined to cause the subject to undergo apnea events,the pillow's air pressure level is changed, and/or the tilt angle of thebed or the mattress is changed, in order to change the patient's postureand prevent an upcoming apnea event, or stop a currently-occurring apneaevent.

Typically, the techniques described herein are practiced in combinationwith techniques described in WO 16/035073 to Shinar, which isincorporated herein by reference. For some applications, a processor asdescribed with reference to FIG. 4 is used in combination with avibrating mechanism and/or an adjustable resting surface. The vibratingmechanism may include a vibrating mechanism disposed underneath mattress26 and/or a vibrating wristwatch.

Typically, the subject is more likely to snore, cough, or have an apneaepisode when the subject is in a supine position. The computer processorreduces the frequency of snoring, coughing, and/or apnea of subject 24by encouraging (e.g., by “nudging”) the subject to move from a supineposition to a different position.

As described hereinabove the computer processor identifies the subject'ssleeping position by analyzing the sensor signal from sensor 22. Inresponse to the identified sleeping position, e.g., in response to theidentified posture being a supine position, the computer processordrives the vibrating mechanism to vibrate, and/or adjusts a parameter(e.g., an angle) of the surface upon which the subject is lying. Thevibration typically nudges the subject to change his posture, while theadjustment of the parameter may nudge the subject to change his postureor actually move the subject into the new posture.

In some applications, an inflatable pillow is used and the computerprocessor adjusts a level of inflation of the inflatable pillow. Forexample, to inhibit coughing and/or snoring, the computer processor maydrive an inflating mechanism to inflate the inflatable pillow, bycommunicating a signal to the inflating mechanism.

As described hereinabove, for some applications, the computer processoris configured to identify a sleep stage of the subject. For some suchapplications, the computer processor drives the vibrating mechanism tovibrate, and/or adjusts the parameter of the resting surface, further inresponse to the identified sleep stage. For example, the computerprocessor may drive the vibrating mechanism to vibrate, and/or adjustthe parameter of the resting surface, in response to the identifiedsleep stage being within 5 minutes of an onset or an end of an REM sleepstage, since at these points in time, the “nudging” or moving is lesslikely to disturb the subject's sleep.

Reference is now made to FIG. 5 is a schematic illustration of a sensorunit 80 disposed under a seat 82 of a vehicle, in accordance with someapplications of the present invention. Sensor unit 80 is configured tomonitor physiological parameters of a subject who is sitting on seat 82,and to generate a sensor signal in response thereto. Typically, thesubject is an operator of the vehicle (e.g., the driver of a car, thepilot of an airplane, the driver of a train, etc.). A computerprocessor, which is typically like computer processor 28 describedherein, is configured to receive and analyze the sensor signal for anyone of a number of reasons.

Typically, the computer processor derives vital signs of the subject(such as heart rate, respiratory rate, and/or heart-rate variability)from the sensor signal. For some applications, the computer processorcompares the subject's vital signs to a baseline of the subject that wasderived during previous occasions when the subject operated the vehicle.In response thereto, the computer processor may determine that thesubject's vital signs have changed substantially from the baseline, thatthe subject is unwell, drowsy, asleep, and/or under the influence ofdrugs or alcohol. In response thereto, the computer processor maygenerate an alert to the driver, or to a remote location (such as to afamily member, and/or to a corporate control center). Alternatively oradditionally, the computer processor may automatically disable thevehicle.

For some applications, the computer processor integrates the analysis ofthe sensor signal from sensor unit 80 with the analysis of a sensorsignal from an additional sensor, which may be disposed in the subject'sbed, for example. For example, the computer processor may determine thatthe subject has not had enough sleep based upon the analysis of thesignals from both sensors. Or, the sensor may derive, from thecombination of the sensor signals, that the subject has had enoughsleep, but appears to be unwell, and/or under the influence of drugs oralcohol. In response thereto, the computer processor may generate analert to the driver, or to a remote location (such as to a familymember, and/or to a corporate control center). Alternatively oradditionally, the computer processor may automatically disable thevehicle.

For some applications, sensor units 80 are disposed underneath more thanone seat in the vehicle. For example, sensor units may be disposedunderneath the seats of a pilot and a co-pilot in an airplane (e.g., asdescribed in WO 16/035073 to Shinar, which is incorporated herein byreference). Or, sensor units may be disposed underneath each of theseats in an airplane or a car. Based upon the sensor signals from thesensor units, the computer processor may determine that a child has beenleft alone in a car, and may generate an alert in response thereto. Forexample, the alert may be generated on the driver's and/or parents'cellular phone(s). Alternatively or additionally, the computer processormay determine the number of people in the car. (It is noted that thesensor is typically configured to distinguish between a person who isdisposed upon the seat and an inanimate object (such as a suitcase, orbackpack) that is disposed upon the seat.) In response thereto, thecomputer processor may generate seatbelt alerts, for example.Alternatively or additionally, the computer processor may automaticallycommunicate with the billing system of a toll road for which prices aredetermined based upon the number of passengers in the car.

Typically, in order to facilitate the above-described applications,sensor unit 80 is configured to generate a sensor signal that is suchthat the computer processor is able to distinguish between artifactsfrom motion of vehicle, and motion that is indicative of physiologicalparameters of the subject. Typically, the sensor unit includes (a) ahousing, (b) at least one first motion sensor disposed within thehousing, such that the first motion sensor generates a first sensorsignal that is indicative of the motion of the vehicle, and (c) at leastone second motion sensor disposed within the housing, such that thesecond motion sensor generates a second sensor signal that is indicativeof the motion of the subject and the motion of the vehicle. The computerprocessor configured to at least partially distinguish between themotion of the subject and the motion of the vehicle by analyzing thefirst and second sensor signals.

For some applications, the first motion sensor is disposed within thehousing, such that the first motion sensor is isolated from the motionof the subject, and/or such that the first motion sensor only detectsmotion that is due to motion of the vehicle. The computer processor atleast partially distinguishes between the motion of the subject and themotion of the vehicle by (a) deriving the motion of the vehicle from thefirst sensor signal(s), and (b) based upon the derived motion of thevehicle, subtracting the vehicular motion (i.e., subtracting the portionof the sensor signal that is generated by the motion of the vehicle)from the sensor signal that is generated by the second sensor(s).

Reference is now made to FIGS. 6A-C are schematic illustrations ofsensor unit 80, in accordance with respective applications of thepresent invention.

As shown in FIG. 6A, for some applications, sensor unit 80 includes ahousing 90 at least a portion 92 of which is flexible. A fluidcompartment 94, which is filled with a gas or a liquid, is disposed onan inner surface of the housing. A first motion sensor 96 (e.g., adeformation sensor, a piezoelectric sensor, and/or an accelerometer) isdisposed on a surface of the fluid compartment, and is configured togenerate a first sensor signal. For some applications (not shown), twoor more first motion sensors are disposed on the surface of the fluidcompartment, and each of the first motion sensors generates a respectivesensor signal. A second motion sensor 98 (e.g., a deformation sensor, apiezoelectric sensor, and/or an accelerometer) is disposed on at leastone inner surface of flexible portion 92 of housing 90. The secondmotion sensor is configured to generate a second sensor signal. For someapplications, as shown, two or more motion sensors 98 are disposed onrespective inner surfaces of flexible portion 92 of housing 90, and eachof motion sensors 98 generates a respective sensor signal. The computerprocessor is configured to at least partially distinguish between themotion of the subject and the motion of the vehicle by analyzing thefirst and second sensor signals.

Typically, fluid compartment 94 isolates first motion sensor 96 frommotion of the subject who is sitting on the seat, such that motionsensor 96 only detects motion that is due to motion of the vehicle.Second motion sensor(s) detects both motion of the vehicle, and motionof the subject, the motion of the subject being conveyed to the secondmotion sensor(s) via the flexible portion of the housing. Thus, thecomputer processor at least partially distinguishes between the motionof the subject and the motion of the vehicle by (a) deriving the motionof the vehicle from the first sensor signal, and (b) based upon thederived motion of the vehicle, subtracting the vehicular motion (i.e.,subtracting the portion of the sensor signal that is generated by themotion of the vehicle) from the sensor signal that is generated by thesecond sensor(s).

As shown in FIGS. 6B and 6C, for some applications, sensor unit 80includes a housing 100 that includes a flexible portion 102 and a rigidportion 104. At least one first motion sensor(s) 106 (e.g., adeformation sensor, a piezoelectric sensor, and/or an accelerometer) isdisposed on at least one inner surface of the rigid portion of thehousing, and is configured to generate a first sensor signal. For someapplications, as shown in FIG. 6C, two or more first motion sensors aredisposed on respective inner surfaces of the rigid portion of thehousing, and each of motion sensors 106 generates a respective sensorsignal. At least one second motion sensor 108 (e.g., a deformationsensor, a piezoelectric sensor, and/or an accelerometer) is disposed onat least one inner surface of flexible portion 102 of housing 100. Thesecond motion sensor is configured to generate a second sensor signal.For some applications, as shown in FIGS. 6B and 6C, two or more motionsensors 108 are disposed on respective inner surfaces of flexibleportion 102 of housing 100, and each of motion sensors 108 generates arespective sensor signal. The computer processor is configured to atleast partially distinguish between the motion of the subject and themotion of the vehicle by analyzing the first and second sensor signals.

Typically, the rigidity of the rigid portion of the housing isolatesfirst motion sensor(s) 106 from motion of the subject who is sitting onthe seat, such that first motion sensor(s) 106 only detects motion thatis due to motion of the vehicle. Second motion sensor(s) detects bothmotion of the vehicle, and motion of the subject, the motion of thesubject being conveyed to the second motion sensor(s) via the flexibleportion of the housing. Thus, the computer processor at least partiallydistinguishes between the motion of the subject and the motion of thevehicle by (a) deriving the motion of the vehicle from the first sensorsignal(s), and (b) based upon the derived motion of the vehicle,subtracting the vehicular motion (i.e., subtracting the portion of thesensor signal that is generated by the motion of the vehicle) from thesensor signal that is generated by the second sensor(s).

Typically, the techniques described herein are practiced in combinationwith techniques described in WO 16/035073 to Shinar, which isincorporated herein by reference. For some applications, a sensor unitas described with reference to FIGS. 5-6C is used in an airplane, andthe computer processor generates one or more of the following outputs,based upon analysis of the sensor signal:

(a) An alert may be generated if, by analyzing the sensor signal, thecomputer processor identifies an elevated stress level of a subject,e.g., by identifying an elevated heart rate, and/or a decreased strokevolume, e.g., as described in WO 2015/008285 to Shinar, which isincorporated herein by reference. For example, in response to the pilotexperiencing an elevated stress level, the computer processor maygenerate an alert to another member of the flight crew, and/orindividuals on the ground. The computer processor may also analyze thesignal of the co-pilot, and generate an alert in response to both thepilot and co-pilot experiencing an elevated stress level, since thepresence of an elevated stress level in both individuals at the sametime is likely to be indicative of an emergency situation. Similarly, analert may be generated if two or more passengers experience an elevatedstress level at the same time.

(b) An alert may be generated if, by analyzing the sensor signal, thecomputer processor identifies that it is likely that the subject isexperiencing, or will soon experience, a clinical event, such as a heartattack. For example, if the pilot or one of the passengers isexperiencing a heart attack, members of the flight crew, and/or aphysician who is travelling on the airplane, may be alerted to thesituation.

(c) An alert may be generated if, by analyzing the sensor signal, thecomputer processor identifies that it is at least somewhat likely thatthe subject is a carrier of a disease, such as severe acute respiratorysyndrome (SARS). For example, if the computer processor identifies achange in the baseline heart rate of the subject without any correlationto motion of the subject, the computer processor may ascertain that thesubject has likely experienced a rapid change in body temperature, whichmay indicate that the subject is sick. (The baseline heart rate istypically an average heart rate over a period of time, e.g., 1-2 hours.)In response, the computer processor may alert the flight crew to isolatethe subject.

(d) An alert may be generated if, by analyzing the sensor signal, thecomputer processor identifies that the subject (in particular, the pilotor co-pilot) is drowsy or sleeping.

(e) A sleep study may be performed. For example, the computer processormay analyze the sensor signals from various passengers, and identifywhich passengers were sleeping at which times. In response, the computerprocessor may generate an output to help the airline improve thesleeping conditions on their aircraft (e.g., by reducing lighting, orincreasing leg room).

The computer processor may also control the lighting, temperature, orother cabin-environment parameters, in order to facilitate a morepleasant travelling experience. For example, upon detecting that asignificant number of passengers are sleeping or are trying to fallasleep, the lights in the cabin may be dimmed, and/or the movie that isplaying may be stopped. Alternatively or additionally, meals may beserved to the passengers only if a given number of passengers are awake.To help prevent deep vein thrombosis (DVT), passengers may be promptedto stand up and take a walk, if the computer processor detects that theyhave been sitting in place for too long.

Reference is now made to FIGS. 7A-B, which are schematic illustrationsof subject-monitoring apparatus, in accordance with some applications ofthe present invention. Components of subject-monitoring apparatus 20 areas described hereinabove with reference to FIG. 1. For someapplications, as shown in FIG. 7B sensor 22 is disposed under a chair111 that the subject sits upon, and is configured to monitor the subjectwhile the subject is sitting on the chair, in the manner describedhereinabove, mutatis mutandis. For some applications techniquesdescribed herein are practiced in combination with techniques describedin WO 16/035073 to Shinar, which is incorporated herein by reference.

Subject-monitoring apparatus 20 comprises a sensor 22, which isgenerally as described hereinabove, and is configured to monitor subject24. Subject-monitoring apparatus 20 includes a control unit, which istypically a computer processor, such as computer processor 28 describedhereinabove. As described hereinabove, computer processor typicallycommunicates with a memory 29. The computer processor is typically acontrol unit that performs the algorithms described herein, includinganalyzing the signal from sensor 22. It is noted that, in general, inthe specification and claims of the present application, the terms“computer processor” and “control unit” are used interchangeably, sincesteps of the techniques described herein are typically performed by acomputer processor that functions as a control unit. Therefore, thepresent application refers to component 28 both as a “computerprocessor” and a “control unit.”

In response to the analyzing the signal from sensor 22, computerprocessor 28 controls a property (e.g., the content, genre, volume,frequency, and/or phase-shift) of a sound signal, and drives a speaker110 to play the sound signal. Typically, as described hereinbelow, theproperty of the sound signal is controlled such as to help the subjectfall asleep or remain asleep.

For example, if the subject is trying to fall asleep, the computerprocessor may select a sound signal of the “relaxing nature sounds”genre, and may further select the content of the signal to be the soundof waves hitting the seashore. The computer processor may further setthe frequency of the sound signal (e.g., the frequency of the waves) toan offset less than the subject's current heart rate or respiratoryrate, in order to facilitate slowing of the subject's heart rate and/orrespiratory rate. In some applications, the computer processor controlsthe offset, in response to analyzing the sensor signal; for example, asthe heart rate of the subject approaches a target “relaxed” heart rate,the computer processor may reduce the offset, such that the frequency ofthe sound signal is very close to or identical with the subject's heartrate. As the subject begins to fall asleep, the computer processor mayreduce the volume of the sound signal.

In some applications, the computer processor controls a phase-shift ofthe sound signal with respect to a cardiac signal and/or a respiratorysignal of the subject. For example, the computer processor may cause thesound of a wave hitting the seashore to occur a given amount of time(e.g., 300 milliseconds) before or after each heartbeat of the subject,or a given amount of time (e.g., 1 second) after each expiration of thesubject.

In some applications, the computer processor ascertains that the subjectis trying to fall asleep, at least in response to analyzing the sensorsignal. For example, by analyzing the sensor signal, the computerprocessor may ascertain that the subject is awake and is exhibiting alarge amount of movement indicative of restlessness in bed.Alternatively or additionally, the ascertaining is in response to one ormore other factors, such as a signal from a light sensor that indicatesa low level of ambient light in the room, and/or the time of day. Inresponse to ascertaining that the subject is trying to fall asleep, thecomputer processor controls the property of the sound signal, asdescribed hereinabove.

In some applications, by analyzing the sensor signal, the computerprocessor ascertains a sleep stage of the subject, and controls theproperty of the sound signal in response to the ascertained sleep stage.For example, in response to ascertaining that the subject has entered aslow-wave (i.e., deep) sleep stage, the volume of the sound signal maybe reduced to a relatively low level (e.g., zero). (In identifying asleep stage of a subject, as described throughout the presentapplication, the computer processor may use one or more of thetechniques described in (a) US 2007/0118054 to Pinhas (now abandoned),and/or (b) Shinar et al., Computers in Cardiology 2001; Vol. 28:593-596, and (c) Shinar Z et al., “Identification of arousals usingheart rate beat-to-beat variability,” Sleep 21(3 Suppl):294 (1998), eachof which is incorporated herein by reference.)

Typically, the computer processor controls the property of the soundsignal further in response to a historical physiological parameter ofthe subject that was exhibited in response to a historical sound signal.For example, the computer processor may “learn” the subject's typicalresponses to particular sound-signal properties, and control the soundsignal in response thereto. Thus, for example, if the subject hashistorically responded well to a “relaxing nature sounds” genre, butless so to a “classical music” genre, the computer processor may selectthe former genre for the subject. To determine whether the subject hashistorically responded well to particular properties of the soundsignal, the computer processor looks at some or all of historicalphysiological parameters such as a quality of sleep, atime-to-fall-asleep, a heart-rate-variability, a change in heart rate, achange in respiratory rate, a change in heart-rate-variability, a changein blood pressure, a rate of change in heart rate, a rate of change inrespiratory rate, a rate of change in heart-rate-variability, and a rateof change in blood pressure.

In some applications, the computer processor controls the frequency ofthe sound signal by synthesizing the sound signal, or by selecting apre-recorded sound signal that has the desired frequency; in otherwords, the computer processor selects the content of the signal, withoutthe user's input. In other applications, the computer processor selectscontent of the sound signal in response to a manual input, e.g., aninput entered via user interface device 35 (FIG. 1). For example, thesubject may select a particular piece of classical music, and thecomputer processor may then control properties (such as the frequency,i.e., the tempo) of that particular piece. This may be done, forexample, using appropriate software, such as Transcribe!™ by SeventhString Software of London, UK.

For some applications, in response to parameters of the signal detectedby sensor 22, the computer processor controls a property of light (suchas intensity, flicker frequency, or color) emitted by a light 112 in agenerally similar manner to that described with respect to controllingthe sound that is generated by speaker 110, mutatis mutandis. Forexample, the computer processor may select a light signal that causesthe subject to enter a relaxed state, in response to detecting that thesubject is trying to fall asleep. Alternatively or additionally, thecomputer processor may modulate the property of the light at a frequencyof modulation that is based upon the subject's current heart rate orrespiratory rate, in order to facilitate slowing of the subject's heartrate and/or respiratory rate, as described hereinabove with respect tothe sound signal. Further alternatively or additionally, the computerprocessor may ascertain a sleep stage of the subject, and modulate theproperty of the light in response to the ascertained sleep stage. Forsome applications, the computer processor controls the property of thelight further in response to a historical physiological parameter of thesubject that was exhibited in response to a historical light signal. Forexample, the computer processor may “learn” the subject's typicalresponses to particular light-signal properties, and control the lightin response thereto. The computer processor may control parameters oflight 112, as an alternative to, or in addition to, controllingproperties of the sound that is generated by speaker 110.

For some applications, in response to parameters of the signal detectedby sensor 22, the computer processor controls a property of light (suchas intensity, flicker frequency, or color) that is emitted by a screen122 of a device that the subject is using in a generally similar mannerto that described with respect to controlling the sound that isgenerated by speaker 110, mutatis mutandis. For example, the device maybe a laptop computer 32 (FIG. 1), a tablet device 34 (FIG. 1), asmartphone 36 (FIG. 7B), and or a TV 124 (FIG. 7B). For example, thecomputer processor may select a light signal that causes the subject toenter a relaxed state, in response to detecting that the subject istrying to fall asleep. Alternatively or additionally, the computerprocessor may modulate the property of the light at a frequency ofmodulation that is based upon the subject's current heart rate orrespiratory rate, in order to facilitate slowing of the subject's heartrate and/or respiratory rate, as described hereinabove with respect tothe sound signal. Further alternatively or additionally, the computerprocessor may ascertain a sleep stage of the subject, and modulate theproperty of the light in response to the ascertained sleep stage. Forsome applications, the computer processor controls the property of thelight further in response to a historical physiological parameter of thesubject that was exhibited in response to a historical light signal. Forexample, the computer processor may “learn” the subject's typicalresponses to particular light-signal properties, and control the lightin response thereto. The computer processor may control parameters oflight emitted by screen 122, as an alternative to, or in addition to,controlling parameters of the sound that is generated by speaker 110,and/or light that is generated by light 112.

For some applications, a vibrating element 126 is disposed underneath asurface of chair 111 upon which the subject sits. Alternatively (notshown), a vibrating element may be disposed underneath the surface ofthe bed upon which the subject lies. For some applications, in responseto parameters of the signal detected by sensor 22, the computerprocessor controls a property of the vibration (such as vibratingfrequency, or a strength of vibration) that is applied to the subject bythe vibrating element, in a generally similar manner to that describedwith respect to controlling the sound that is generated by speaker 110,mutatis mutandis. For example, the computer processor may select avibration signal that causes the subject to enter a relaxed state, inresponse to detecting that the subject is trying to fall asleep.Alternatively or additionally, the computer processor may modulate theproperty of the vibration at a frequency of modulation that is basedupon the subject's current heart rate or respiratory rate, in order tofacilitate slowing of the subject's heart rate and/or respiratory rate,as described hereinabove with respect to the sound signal. Furtheralternatively or additionally, the computer processor may ascertain asleep stage of the subject, and modulate the property of the vibrationin response to the ascertained sleep stage. For some applications, thecomputer processor controls the property of the vibration further inresponse to a historical physiological parameter of the subject that wasexhibited in response to a historical vibration signal. For example, thecomputer processor may “learn” the subject's typical responses toparticular vibration-signal properties, and control the vibratingelement in response thereto. The computer processor may controlparameters of the vibration of the vibrating element, as an alternativeto, or in addition to, controlling parameters of the sound that isgenerated by speaker 110, and/or light that is generated by light 112 orby screen 122.

It is noted that, typically, for any of the embodiments described withreference to FIGS. 7A-B, in response to analysis of the signal fromsensor 22, computer processor controls a property of astimulus-providing device, in a manner that changes a physiologicalparameter of the subject, such as the subject's heart rate, respirationrate, or sleep latency period. The stimulus-providing device may providean audio stimulus (e.g., speaker 110), a visual stimulus (e.g., light112 or screen 122), or a tactile stimulus (e.g., vibrating element 126).Typically, the stimulus is provided to the subject in a manner that doesnot require any compliance by the user, during the provision of thestimulus to the subject. (Prior to the monitoring of the subject andproviding the stimulus to the subject, certain actions (such aspurchasing the sensor, placing the sensor under the subject's mattressor chair, downloading software for use with the subject-monitoringapparatus, configuring software for use with the subject-monitoringapparatus, or turning on the stimulus providing device) may need to beperformed. The term “without requiring subject compliance” should not beinterpreted as excluding such actions.) Typically, the subject mayperform routine activities (such as browsing the internet, or watchingTV), and while the subject is performing routine activities, thecomputer processor automatically controls a property of the stimulusthat is provided to the subject in the above-described manner.Furthermore, typically the stimulus is provided to the subject in mannerthat does not require the subject to consciously change thephysiological parameter upon which the stimulus has an effect. Rather,the stimulus is provided to the subject such that the physiologicalparameter of the subject is changed without requiring the subject toconsciously adjust the physiological parameter.

FIG. 8 is a flowchart showing steps that are performed by a computerprocessor in order to monitor a subject who is pregnant, in accordancewith some applications of the present invention. A pregnant woman'sheart rate is typically expected to increase during pregnancy and behigher than the woman's heart rate prior to pregnancy. For someapplications, during a calibration phase, a female subject is monitoredusing sensor 22 before pregnancy. Computer processor receives the sensorsignal (step 130), analyzes the sensor signal (step 132), and, basedupon the analysis, determines a baseline heart rate (e.g., a baselineaverage daily heart rate, or a baseline heart rate at a given timeperiod of the day, and/or at a given period of the subject's circadiancycle) for the subject (step 134). Based upon the baseline heart rate,the computer processor determines a pregnancy heart rate measure, whichis indicative of what the subject's heart rate is expected to be (e.g.,what the average daily heart rate, or the heart rate at a given timeperiod of the day, and/or at a given period of the subject's circadiancycle is expected to be) during a healthy pregnancy (step 136).Typically, the computer processor determines a range of heart rates thatare considered to be healthy when the subject is pregnant, based uponthe determined baseline heart rate. When the subject is pregnant, duringa pregnancy monitoring phase, the computer processor receives the sensorsignal (step 138), analyzes the sensor signal (step 140), and based uponthe analysis of the signal determines the subject's heart rate (step142). The computer processor compares the heart rate to the pregnancyheart rate measure that was determined based upon the baseline heartrate (step 144). Based on the comparison, the computer processordetermines whether the subject's pregnancy is healthy. For someapplications, the computer processor generates an output (e.g., analert) on an output device (as described hereinabove), in response tothe comparison (step 146). For some applications, in response todetecting that the subject's heart rate has returned to thepre-pregnancy baseline heart rate, the computer processor generates anoutput that is indicative of a recommendation to visit a physician.

Reference is now made to FIGS. 9A-C, which show histograms of patients'cardiac interbeat intervals that were recorded in accordance with someapplications of the present invention. As described hereinabove, forsome applications, sensor 22 performs monitoring of the subject withoutcontacting the subject or clothes the subject is wearing, and/or withoutviewing the subject or clothes the subject is wearing. For someapplications, the sensor is configured to detect the subject's cardiaccycle, using techniques as described herein. In some cases, typicallydue to the non-contact nature of the sensing, some of the subject'sheartbeats are not reliably detected. For some such applications, foreach heartbeat, the computer processor determines a quality indicatorthat indicates the quality of the sensed heartbeat. For example, thecomputer processor may determine the signal-to-noise ratio of thesignal, and compare the signal-to-noise ratio to a threshold.

For some applications, the computer processor selects a subset ofheartbeats, based upon the qualities of the heartbeats, and some stepsof the subsequent analysis (as described herein) are performed only withrespect to the subset of heartbeats. For some applications, only incases in which two consecutive heart beats have a quality indicator thatexceeds a threshold, the interbeat interval is calculated and/or isselected for use in subsequent analysis. For some applications, thecomputer processor builds a histogram of the selected interbeatintervals. The computer processor analyzes the selected interbeatintervals over a period of time, and in response thereto, the computerprocessor determines whether the subject is healthy or is suffering fromarrhythmia, which type of arrhythmia the subject is suffering from,and/or identifies or predicts arrhythmia episodes. For example, thecomputer processor may build a histogram of the selected interbeatintervals and may perform the above-described steps by analyzing thehistogram.

FIGS. 9A-C show sample histograms that were constructed using theabove-described technique. The x-axes of the histograms measure the timeat which the interbeat interval measurement was recorded, the y-axesmeasure the interbeat interval and the color legend measures theamplitude of the histogram at each interbeat interval (with a lightercolor representing greater amplitude). FIG. 9A shows measurementsrecorded from a healthy subject, there being only one peak atapproximately 900 ms. FIG. 9B is the histogram of an arrhythmic subject,the histogram including two dominant peaks shown by the two light linesat approximately 450 ms and 800 ms. FIG. 9C is the histogram of asubject who starts with a normal cardiac rhythm and at about an x-axistime of 5,500 sec. starts to show an arrhythmia that is manifested bythe much wider distribution of the histogram.

In accordance with the above, for some applications, in response to thecomputer processor identifying two distinct peaks in a histogram that isplotted using the techniques described herein (or performing anequivalent algorithmic operation), an alert is generated that anarrhythmia event may be taking place. Alternatively or additionally, thecomputer processor may generate an alert in response to identifying thatthe width of a peak of a histogram exceeds a threshold (or performing anequivalent algorithmic operation). For example, the width of the peakmay be compared to a threshold that is determined based upon populationaverages according to the age and or other indications of the subject(such as, a level of fitness of the subject).

For some applications, in response to the computer processor identifyingtwo distinct peaks in a histogram that is plotted using the techniquesdescribed herein (or performing an equivalent algorithmic operation),the computer processor performs the following steps. The computerprocessor identifies heartbeats belonging to respective interbeatinterval groups (i.e., which heartbeats had an interbeat interval thatcorresponds to a first one of the peaks, and which heartbeats had aninterbeat interval corresponding to the second one of the peaks.) Theaverage amplitude of the signal of each of these groups is thencalculated. For some applications, the computer processor generates anoutput that is indicative of the average amplitude of each of the peaks,and/or the interbeat interval of each of the peaks. Alternatively oradditionally, based upon these data, the computer processorautomatically determines a condition of the subject. For example, thecomputer processor may determine which category of arrhythmia thesubject is suffering from, e.g., atrial fibrillation or ventricularfibrillation.

It is noted that, although the analysis of the interbeat intervals isdescribed as being performed using histogram analysis, the techniquesdescribed herein may be combined with other types of analysis that wouldyield similar results, mutatis mutandis. For example, the computerprocessor may perform algorithmic steps that do not include a step ofgenerating a histogram, but which analyze the subject's interbeatinterval over time, in a similar manner to that described hereinabove.

Reference is now made to FIG. 10, which shows components of a subject'scardiac cycle that were detected, in accordance with some applicationsof the present invention. For some applications, sensor 22 is used tomonitor a cardiac-related signal of the subject. For some applications,a bank of matched filters with varying filter parameters (e.g., varyingwidth properties) is applied to the raw signal, and one of the filteredsignals is selected by the computer processor. For example, the filterhaving the greatest signal-to-noise ratio may be selected, by selectingthe filter that generates the highest ratio of the main lobe to the sidelobes in the filtered signal. Typically, the filters are designed tohave a main lobe with full-width-half-maximum value that fits a humanbiological beat as recorded with the contact free sensor under themattress. The bank of filters typically includes filters having a rangeof relevant full-width-half-maximum values for biological signals.Typically, the filters are zero-mean, e.g., in order to remove anytrends, movements or respiration.

Typically, the selection of which filter to use is repeated in responseto certain events. For some applications, the selection of a filter isrepeated if the signal quality falls below a threshold. Alternatively oradditionally, the filter selection is repeated at fixed times intervals(e.g., once every 5 minutes, ten minutes, or 15 minutes). Further,alternatively or additionally, the filter selection is repeated inresponse to detecting motion of the subject, e.g., large body motion ofthe subject. For example, in response to the sensor signal indicatingthat the subject has undergone motion (e.g., large body motion), thecomputer processor may perform the filter selection.

Referring to FIG. 10, a signal that was detected using the abovedescribed technique is shown above the corresponding ECG signal. It maybe observed that certain cardiac events, which correlate with the ECGsignal, may be extracted from the sensor signal. For example, thefollowing mechanical events can typically be extracted from the sensorsignal: mitral valve closure (MC), aortic valve opening (AO), systolicejection (SE), aortic valve closure (AC), and mitral valve opening (MO).Therefore, for some applications, a cardiac signal that is detectedusing techniques described herein is analyzed by the computer processor,and one or more of the events are identified. For some applications, inthis manner, the computer processor monitors mechanical functioning ofthe heart. For example, the computer processor may use the identifiedevents to measure the subject's left ventricular ejection time. For someapplications, the computer processor analyzes the subject's cardiaccycle, by using the above-described technique in combination with ECGsensing.

In general, computer processor 28 may be embodied as a single computerprocessor 28, or a cooperatively networked or clustered set of computerprocessors. Computer processor 28 is typically a programmed digitalcomputing device comprising a central processing unit (CPU), randomaccess memory (RAM), non-volatile secondary storage, such as a harddrive or CD ROM drive, network interfaces, and/or peripheral devices.Program code, including software programs, and data are loaded into theRAM for execution and processing by the CPU and results are generatedfor display, output, transmittal, or storage, as is known in the art.

Typically, computer processor 28 is connected to one or more sensors viaone or more wired or wireless connections. Computer processor 28 istypically configured to receive signals (e.g., motion signals) from theone or more sensors, and to process these signals as described herein.In the context of the claims and specification of the presentapplication, the term “motion signal” is used to denote any signal thatis generated by a sensor, upon the sensor sensing motion. Such motionmay include, for example, respiratory motion, cardiac motion, or otherbody motion, e.g., large body-movement. Similarly, the term “motionsensor” is used to denote any sensor that senses motion, including thetypes of motion delineated above.

Applications of the invention described herein can take the form of acomputer program product accessible from a computer-usable orcomputer-readable medium (e.g., a non-transitory computer-readablemedium) providing program code for use by or in connection with acomputer or any instruction execution system, such as computer processor28. For the purposes of this description, a computer-usable or computerreadable medium can be any apparatus that can comprise, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system (or apparatus or device) or apropagation medium. Typically, the computer-usable or computer readablemedium is a non-transitory computer-usable or computer readable medium.

Examples of a computer-readable medium include a semiconductor or solidstate memory, magnetic tape, a removable computer diskette, a randomaccess memory (RAM), a read-only memory (ROM), a rigid magnetic disk andan optical disk. Current examples of optical disks include compactdisk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) andDVD.

A data processing system suitable for storing and/or executing programcode will include at least one processor (e.g., computer processor 28)coupled directly or indirectly to memory elements (e.g., memory 29)through a system bus. The memory elements can include local memoryemployed during actual execution of the program code, bulk storage, andcache memories which provide temporary storage of at least some programcode in order to reduce the number of times code must be retrieved frombulk storage during execution. The system can read the inventiveinstructions on the program storage devices and follow theseinstructions to execute the methodology of the embodiments of theinvention.

Network adapters may be coupled to the processor to enable the processorto become coupled to other processors or remote printers or storagedevices through intervening private or public networks. Modems, cablemodem and Ethernet cards are just a few of the currently available typesof network adapters.

Computer program code for carrying out operations of the presentinvention may be written in any combination of one or more programminglanguages, including an object oriented programming language such asJava, Smalltalk, C++ or the like and conventional procedural programminglanguages, such as the C programming language or similar programminglanguages.

It will be understood that each block of the flowcharts shown in FIGS.3, 4, and 8, and combinations of blocks in the flowcharts, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer (e.g., computerprocessor 28) or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartsand/or algorithms described in the present application. These computerprogram instructions may also be stored in a computer-readable medium(e.g., a non-transitory computer-readable medium) that can direct acomputer or other programmable data processing apparatus to function ina particular manner, such that the instructions stored in thecomputer-readable medium produce an article of manufacture includinginstruction means which implement the function/act specified in theflowchart blocks and algorithms. The computer program instructions mayalso be loaded onto a computer or other programmable data processingapparatus to cause a series of operational steps to be performed on thecomputer or other programmable apparatus to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowcharts and/oralgorithms described in the present application.

Computer processor 28 is typically a hardware device programmed withcomputer program instructions to produce a special purpose computer. Forexample, when programmed to perform the algorithms described withreference to FIG. 3, computer processor 28 typically acts as a specialpurpose temperature control computer processor, when programmed toperform the algorithms described with reference to FIG. 4, computerprocessor 28 typically acts as a special purpose apnea monitoringprocessor, and when programmed to perform the algorithms described withreference to FIG. 8, computer processor 28 typically acts as a specialpurpose pregnancy monitoring processor. Typically, the operationsdescribed herein that are performed by computer processor 28 transformthe physical state of memory 29, which is a real physical article, tohave a different magnetic polarity, electrical charge, or the likedepending on the technology of the memory that is used.

Techniques described herein may be practiced in combination withtechniques described in one or more of the following patents and patentapplications, which are incorporated herein by reference. In someapplications, techniques and apparatus described in one or more of thefollowing patents and patent applications, which are incorporated hereinby reference, are combined with techniques and apparatus describedherein:

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It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

1-40. (canceled)
 41. Apparatus for monitoring a subject, the apparatuscomprising: a sensor, configured to monitor the subject withoutcontacting the subject or clothes the subject is wearing, and withoutviewing the subject or clothes the subject is wearing, and to generate asensor signal in response to the monitoring; and a computer processor,configured to: receive the sensor signal, extract from the sensor signala plurality of heartbeats of the subject, and, for each of the extractedheartbeats, an indication of a quality of the extracted heartbeat,select a subset of heartbeats, based upon the qualities of the extractedheartbeats, for only the subset of heartbeats, determine interbeatintervals between adjacent heartbeats, in response thereto, determine aphysiological state of the subject, and generate an output in responsethereto.
 42. (canceled)
 43. The apparatus according to claim 41, whereinthe computer processor is configured to extract the indication of thequality of the extracted heartbeat by determining a signal-to-noiseratio of the sensor signal.
 44. The apparatus according to claim 43,wherein the computer processor is configured to select the subset ofheartbeats by: (a) comparing the signal-to-noise ratio of the sensorsignal to a threshold, and (b) selecting pairs of consecutive heartbeatsbased on the signal-to-noise ratio exceeding the threshold.
 45. Theapparatus according to claim 41, wherein the computer processor isconfigured to select the subset of heartbeats by comparing theindication of the quality of each extracted heartbeat to a threshold,and selecting pairs of consecutive heartbeats having a quality indicatorthat exceeds the threshold.
 46. The apparatus according to claim 41,wherein subsequently to determining the interbeat intervals betweenadjacent heartbeats, the computer processor is configured to build ahistogram of the interbeat intervals for the subset of heartbeats,analyze the histogram, and in response thereto, determine thephysiological state of the subject.
 47. The apparatus according to claim46, wherein, in response to analyzing the histogram, the computerprocessor is configured to determine whether the subject is healthy oris suffering from arrhythmia.
 48. The apparatus according to claim 47,wherein in response to determining that the subject is suffering fromarrhythmia, the computer processor is further configured to determinewhich type of arrhythmia the subject is suffering from.
 49. Theapparatus according to claim 46, wherein, in response to analyzing thehistogram, the computer processor is configured to predict an arrythmiaepisode.
 50. The apparatus according to claim 46, wherein, in responseto analyzing the histogram, the computer processor is configured toidentify that an arrhythmia event may be occurring.
 51. The apparatusaccording to claim 50, wherein the computer processor is configured toidentify that the arrhythmia event may be taking place in response tothe computer processor identifying two distinct peaks in the histogram.52. The apparatus according to claim 51, wherein, in response toidentifying two distinct peaks in the histogram, the computer processoris configured to: identify heartbeats belonging to respective interbeatinterval groups by identifying which heartbeats had an interbeatinterval corresponding to a first one of the peaks, and which heartbeatshad an interbeat interval corresponding to the second one of the peaks;and calculate the average amplitude of the sensor signal of eachinterbeat interval group.
 53. The apparatus according to claim 52,wherein the computer processor is configured to generate an output thatis indicative of the average amplitude of each of the peaks.
 54. Theapparatus according to claim 52, wherein the computer processor isconfigured to generate an output that is indicative of the averageamplitude of the interbeat interval of each of the peaks.
 55. Theapparatus according to claim 52, wherein, based upon the averageamplitude of the sensor signal of each interbeat interval group, thecomputer processor is further configured to determine a category ofarrhythmia that the subject is suffering from selected from the groupconsisting of: atrial fibrillation and ventricular fibrillation.
 56. Theapparatus according to claim 50, wherein the computer processor isconfigured to identify that the arrhythmia event may be occurring inresponse to the computer processor identifying a peak in the histogramthat has a width that exceeds a threshold width.
 57. The apparatusaccording to claim 56, wherein the computer processor is configured todetermine the threshold width based on population averages regarding aparameter of the subject indicated by the subject.
 58. The apparatusaccording to claim 57, wherein the parameter of the subject is anindication of the subject's age or an indication of a level of fitnessof the subject.